Rovers, who led 24-12 at the break, are now one match from reaching Super League for the first time.

In Sunday's other match, Whitehaven thrashed Batley 30-0 and will now play Widnes next weekend for the right to meet the Robins in the final.

The Grand Final takes place at Warrington's ground on 8 October.

Hull KR scored all of their tries in the first half through Makali Aizue, Jon Steel, Ben Cockayne and Ben Fisher, while Gareth Morton kicked four goals.

The Vikings replied with tries from Damian Blanch and Darryl Cardiss and one goal each from Mick Nanyn and Gavin Dodd.

The visitors added further scores from Aaron Summers and Marc Smith, but Morton kicked two penalties and Scott Murrell landed a last-minute drop goal to secure victory for Rovers.

Mark Leafa crossed twice for Whitehaven while John Duffy, Spencer Miller and Craig Calvert also touched down. Carl Rudd kicked five goals.

If Haven go on to win the Grand Final, it will hand a Super League reprieve to Castleford Tigers.

The Cumbrian side were told in August that their stadium facilities and business documentation did not meet the required Super League standard.

In the event of Whitehaven winning the Grand Final, Castleford will remain in Super League.

Meanwhile, Swinton will play Celtic Crusaders for a place in the National League Two promotion final after a stunning 27-14 win at Featherstone.

The Lions had not won at the Lionheart Stadium since 1965 but clinched victory in the second half with Darren Woods, Kris Smith and Andy Saywell scoring crucial tries.